Apparatus for heating a building using a heat pipe

ABSTRACT

An apparatus, based on a heat pipe, is provided for heating a building having at least one enclosed space that is bounded by a wall. The apparatus includes a plurality of passive heat transfer modules distributed along a dimension of the building and a hot source. Each passive heat transfer module includes a closed volume filled with two-phrase heat transfer fluid, at least one evaporator located outside of the enclosed space, downwardly directed heaters formed from a condenser tube, and an adiabatic circuit connecting an outlet of the evaportor and an inlet of the condenser tube. The heaters are spaced from the evaporator and located inside and at a top of the enclosed space to be heated. The hot source is located outside of the enclosed space to be heated but in heat exchange relationship with the evaporator. The hot source includes a lagged duct for the flow of a gas stream at high temperature and the adiabatic circuit passes through the wall of the enclosed space to be heated.

BACKGROUND OF THE INVENTION

The present invention relates to the heating of a building, and moreparticularly of a building for industrial use, for example a workshop.

Document FR-A-2,320,501 has described and proposed an apparatus forheating a building using a heat pipe, for example a dwelling,consequently comprising several enclosed spaces or rooms to be heated,each bounded by a wall or equivalent separating means. This heatingapparatus comprises a passive heat transfer module or system, forming aclosed volume filled with a two-phase heat transfer fluid, for example afluoro-chlorinated hydrocarbon. This module comprises, at a low end, anevaporator, located outside the enclosed space or room to be heated, acondenser located at the top inside the same enclosed space, and anadiabatic circuit connecting the outlet of the evaporator to the inletof the condenser, passing through the wall of the enclosed space to beheated, said adiabatic circuit being designed to pass the evaporatedheat transfer fluid from the evaporator to the condenser and to returnthe condensed same fluid from the condenser to the evaporator, all thisby means of a column arranged as a heat pipe. The heating means locatedinside the enclosed space to be heated are solely of the convective typeand are thermally coupled to the condenser.

The apparatus described above appears to be unsuitable for heating anindustrial building.

Document GB-A-764,280 has described an apparatus for heating using aheat pipe, which comprises, as previously:

(a) a passive heat transfer module forming a closed volume filled with atwo-phase heat transfer fluid, comprising at least one evaporator, atleast one condenser and an adiabatic circuit, connecting the outlet ofthe evaporator and the inlet of the condenser, said adiabatic circuitbeing designed to pass the evaporated heat transfer fluid from theevaporator to the condenser and to return the condensed heat transferfluid from the condenser to the evaporator;

(b) a hot source in heat exchange with the evaporator;

(c) heating means thermally coupled to the condenser consistingessentially of means for heating the air or ambient atmosphereconvectively.

SUMMARY OF THE INVENTION

It is known that convective means turn out to be not very effective forheating an enclosed space of large volume, for example of the workshoptype.

The subject of the present invention is therefore an apparatus forheating using a heat pipe, making it possible to heat a building with asatisfactory thermal efficiency which is superior to that usingconventional heating means.

In accordance with the invention, the heating means are located at thetop of the enclosed space to be heated, are directed downward andcombine a thermal-radiation radiative structure which has a relativelylarge developed surface area, thermally coupled to the condenser, andmeans for thermally insulating said radiative structure which arelocated above the condenser and said structure and are dimensioned, withrespect to one another, so that the heat radiatively emitted by saidheating means represents at least 80% of the heat produced by saidmeans.

BRIEF DESCRIPTION OF THE DRAWING

The present invention will now be described with reference to theappended drawing, in which:

FIG. 1 depicts diagrammatically, with partial cutaway, a buildingequipped with a heating apparatus according to the present invention;

FIG. 2 depicts, again diagrammatically, a passive heat transfer moduleforming part of the heating apparatus depicted in FIG. 1;

FIG. 3 depicts, in cross-section on the line III--III of FIG. 2, theheating means forming part of the passive heat transfer module depictedin FIG. 2.

DETAILED DESCRIPTION OF EMBODIMENTS

FIG. 1 depicts a building 14, the roof of which has been removed for thesake of the drawing, having a wall 15 which delimits, on the inside, anenclosed space 1 to be heated. Depending on the length of the building14, several (in this case four) passive heat transfer modules 2according to the invention are distributed so as to heat the inside ofthe building uniformly. The wall 15 of the enclosed space is showndiagrammatically in FIG. 2 by the dot-dash line.

According to FIG. 2, each passive heat transfer module 2 forms a closedvolume filled with a two-phase heat transfer fluid, in this case waterin the form of liquid and vapor. Each module 2 is located on each sideof the wall 15 of the enclosed space to be heated 1, and therefore bothoutside and inside the building 14, and in general comprises:

an evaporator 3, optionally located outside the enclosed space 1 to beheated, and more specifically inside a lagged duct 8 for the flow of agas stream at high temperature, the duct itself lying outside thebuilding 14;

three condensers 41, 42 and 43, supplied via the same distributor 17,these being located inside the enclosed space 1, and more particularlyat the top of the building 14, under the roof (not depicted) andfollowing approximately the slope of the latter;

an adiabatic circuit or pipe 5 passing through the wall 15 of theenclosed space to be heated, connecting the outlet 3a of the evaporator3 to the inlets 41a, 42a and 43a of the condensers 41, 42 and 43respectively, via the distributor 17, said circuit being designed topass the evaporated heat transfer fluid from the evaporator 3 to theaforementioned condensers and to return the condensed heat transferfluid as a countercurrent from the condensers 41 to 43 to the evaporator3.

The lagged duct 8 for the flow of the gas stream at high temperatureconstitutes a hot source 6 common to all the passive heat transfermodules 2. For this purpose, the evaporators 3 of the four heat transfermodules 2 are located in the lagged duct 8, in heat exchange with thegas stream flowing in the latter. A burner 9, for example one burning acombustible gas, is located at one end of the flow duct 8, upstream ofall the evaporators 3. Thus, with an intake of ambient air from theatmosphere, a gas stream at high temperature flows in the duct 8 in thedirection and sense which are established by the arrows 16.

According to FIG. 2, each passive heat transfer module 2 comprisesheating means located at the top of the enclosed space 1 to be heated,and directed downward. Each heating means combines a radiative structure71, 72 or 73 designed to radiate thermally, downward, having arelatively large developed surface area, and thermally coupled, forexample conductively, to a condenser 41, 42 or 43 respectively. Morespecifically, as shown in FIGS. 1 through 3, each condenser 41 comprisesa tube closed at one end, 41b. Condensers 42 and 43 have like structure(unshown). The radiative structures 71, 72 and 73 each comprise twometal flanges, 71a and 71b or 72a and 72b or 73a and 73b, located oneach side of the aforementioned tube and thermally connectedconductively to the latter. As shown in FIG. 3, means 10 for thermallyinsulating each radiative structure 71, 72 and 73 are located above thecondenser 41, 42 and 43 respectively, and above the radiative structure71, 72 and 73 of the same passive heat transfer module 2. The condensers41, 42 and 43, the radiative structures 71, 72 and 73 and the thermalinsulation means 10 are dimensioned, with respect to one another, sothat the heat emitted radiatively by the heating means represents atleast 80% of the heat produced by said heating means.

The evaporator 3 of each heat transfer module 2 comprises a tube 12closed at one end, 12a, located transversely, for example vertically, inthe duct 8 for the flow of the gas stream at high temperature, aplurality of fins 13 lying perpendicular to the axis of the closed tube12.

It stems from the above description that each passive heat transfermodule 2 behaves as a thermosyphon, comprising the evaporator 3, at oneend and at a low level, and three condensers 41 to 43 located, withtheir respective radiative structures 71 to 73, at the other end and ata high level. The evaporator 3 and the aforementioned condensers areconnected together by the adiabatic pipe 5 and the distributor 17 inorder for the vapor phase of the heat transfer fluid to rise (along thedirection of the dotted arrow) and for the liquid phase of the heattransfer fluid to fall as a countercurrent (along the direction of thesolid-line arrow).

According to the present invention, the heat transfer fluid and theinternal pressure in each passive heat transfer module 2 are determinedin order to establish, in operation:

a predetermined temperature of between 110° C. and 250° C., andpreferably of between 140° C. and 160° C., for example 150° C., in thecondenser; and

a temperature of between 400° C. and 600° C., and preferably between450° C. and 550° C., for example 500° C., in the evaporator 3.

Preferably, each heat transfer module 2 is dimensioned so as tocorrespond to the following characteristics:

the closed volume being at most equal to 25 liters, the bore of theadiabatic circuit or pipe 5 is between 3 and 4 cm;

the overall length of the module 2, i.e. the developed length from theevaporator 3 to the condensers 41 to 43, is less than or equal to 15 m.

I claim:
 1. An apparatus for heating a building having at least oneenclosed space to be heated that is bounded by a wall, said apparatuscomprising:a) a plurality of passive heat transfer modules distributedalong a dimension of the building, each passive heat transfer modulecomprising a closed volume filled with a two-phase heat transfer fluid,said module including at least one evaporator; downwardly directedheating means spaced from said evaporator and located inside and at atop of the enclosed space to be heated, said heating means including acondenser tube closed at one end, a radiative flange located on one sideof and conductively connected to said condenser tube, and thermalinsulating means located above said condenser tube and said radiativeflange; and an adiabatic circuit connecting an outlet of said evaporatorand an inlet of said condenser tube, said adiabatic circuit passingevaporated heat transfer fluid from said evaporator to said condensertube and returning condensed heat transfer fluid from said condensertube to said evaporator; and (b) a hot source located in heat exchangerelationship with the evaporator, said hot source comprising a laggedduct for the flow of a gas stream at high temperature, located outsideof the enclosed space to be heated, and the evaporator is located inheat exchange relationship with the gas stream, wherein said evaporatorand said hot source are located outside of said enclosed space, the atleast one evaporator of each of the passive heat transfer modules isrespectively located in said lagged duct for the flow of the gas streamat high temperature, said adiabatic circuit passes through the wall ofthe enclosed space to be heated, and the condenser tube and the heatingmeans are located inside and at the top of the enclosed space to beheated.
 2. The apparatus according to claim 1, wherein a burner islocated at one end of said lagged duct, upstream from said evaporator.3. The apparatus according to claim 1, wherein said evaporator comprisesat least one tube closed at one end and located transversely in thelagged duct, and a plurality of fins lying perpendicular to an axis ofsaid at least one tube of said evaporator.
 4. The apparatus according toclaim 1, wherein the heat transfer fluid and internal pressure in saidpassive heat transfer module provide a condenser temperature of between110° C. and 250° C.
 5. The apparatus according to claim 4, wherein thecondenser temperature is between 140° C. and 160° C.
 6. The apparatusaccording to claim 4, wherein the condenser temperature is about 150° C.7. The apparatus according to claim 4, wherein the heat transfer fluidand the internal pressure in the passive heat transfer module provide anevaporator temperature of between 400° C. and 600° C.
 8. The apparatusaccording to claim 4, wherein the heat transfer fluid and the internalpressure in the passive heat transfer module provide an evaporatortemperature of between 450° C. and 550° C.
 9. The apparatus according toclaim 4, wherein the heat transfer fluid and the internal pressure inthe passive heat transfer module provide an evaporator temperature ofabout 500° C.
 10. The apparatus according to claim 1, wherein saidpassive heat transfer module comprises one evaporator at one end of saidmodule and a plurality of said heating means at the other end of saidmodule, said condenser tubes of said plurality of heating means allbeing connected by a common distributor to said adiabatic circuit. 11.The apparatus according to claim 1, wherein said passive heat transfermodule has a closed volume of no more than 25 liters and a bore of saidadiabatic circuit is between 3 cm and 4 cm in diameter.
 12. Theapparatus according to claim 1, wherein an overall length of saidpassive heat transfer module from said evaporator to said condenser isless than or equal to 15 m.
 13. An apparatus for heating a buildinghaving at least one enclosed space to be heated that is bounded by awall, said apparatus comprising:a) at least one passive heat transfermodule comprising a closed volume filled with a two-phase heat transferfluid, said module including at least one evaporator including at leastone tube closed at one end and a plurality of fins lying perpendicularto an axis of said at least one tube of the evaporator; downwardlydirected heating means spaced from said evaporator and located insideand at a top of the enclosed space to be heated, said heating meansincluding a condenser tube closed at one end, a radiative flange locatedon one side of and conductively connected to said condenser tube, andthermal insulating means located above said condenser tube and saidradiative flange; and an adiabatic circuit connecting an outlet of saidevaporator and an inlet of said condenser tube, said adiabatic circuitpassing evaporated heat transfer fluid from said evaporator to saidcondenser tube and returning condensed heat transfer fluid from saidcondenser tube to said evaporator; and (b) a hot source located in heatexchange relationship with the evaporator, said hot source comprising alagged duct for the flow of a gas stream at high temperature, locatedoutside of the enclosed space to be heated, and the evaporator islocated in heat exchange with the gas stream, wherein said evaporatorand said hot source are located outside of said enclosed space, saidadiabatic circuit passes through the wall of the enclosed space to beheated, and the at least one tube is located transversely in the laggedduct.
 14. The apparatus according to claim 13, wherein a burner islocated at one end of said lagged duct, upstream from said evaporator.15. The apparatus according to claim 13, wherein the heat transfer fluidand internal pressure in said passive heat transfer module provide acondenser temperature of between 110° C. and 250° C.
 16. The apparatusaccording to claim 15, wherein the condenser temperature is between 140°C. and 160° C.
 17. The apparatus according to claim 15, wherein the heattransfer fluid and the internal pressure in the passive heat transfermodule provide an evaporator temperature of between 400° C. and 600° C.18. The apparatus according to claim 15, wherein the heat transfer fluidand the internal pressure in the passive heat transfer module provide anevaporator temperature of between 450° C. and 550° C.
 19. The apparatusaccording to claim 13, wherein said passive heat transfer modulecomprises one evaporator at one end of said module and a plurality ofsaid heating means at the other end of said module, said condenser tubesof said plurality of heating means all being connected by a commondistributor to said adiabatic circuit.
 20. The apparatus according toclaim 13, wherein said passive heat transfer module has a closed volumeof no more than 25 liters and a bore of said adiabatic circuit isbetween 3 cm and 4 cm in diameter.